The present invention relates to a process and a device to determine the tendency of cotton to adhere. In processing cotton, it has been a long-known problem to process sticky fibers as these adhere to each other in drafting and during the spinning process and also tend to form laps on the pressure rollers of the drafting equipment. There are several causes of this adhesion. The so-called "honeydew" which is deposited on the fibers of the open pods is a consideration. This is mainly a secretion of flies and other insects, but also micro-organisms assailing the cotton plant. There is however also the phenomenon whereby the cotton tends to adhere only during its processing. This adhesion is produced by crushed trash particles during ginning, i.e. when separating the cotton fibers from the seed grains.
Whatever the origin of this adhesiveness may be, the effect is however the same, resulting in difficulties in processing such fibers in the spinning process. It is therefore important for the spinning manufacturer to be able to ascertain already when purchasing the cotton whether or not it tends to adhere. Since the different kinds of cotton are mixed together after the harvest, and since the mixing is also a precondition in the spinning plant for a good yarn that meets its application requirements, the danger exists that cotton which tends to adhere may spoil the entire mixture. It is therefore especially important to find out preferably in the raw cotton whether a tendency to adherence exists, so that this fiber material may be eliminated in time or may be subjected to a special treatment by which this adhesion is removed, so that perfect cotton may in no case be mixed together with such cotton tending to adhere.
Lately in particular, the problem with cotton tending to adhere has taken a prominent importance since the fight against parasites has been more and more restricted for reasons of cost but also for ecological reasons. It is therefore especially important to recognize early this cotton which tends to adhere in order to prevent this affected fiber material from being mixed with perfect fiber material.
Different processes for the recognition and evaluation of the adhesion tendency of cotton have already become known. In the "Orcin" test for example, a color test is conducted with a chemical solution. The cotton samples to be thus tested are extracted in soxhlet apparatus with methanol. The methanol extract is taken up with water and is colored by adding the sulfuric acid orcin solution in function of the carbon hydrate contents. With a suitable concentration of the solution, color tones going from lemon yellow to dark red and brown are obtained, and these can be evaluated by colorimetric means. The different colors result from the total sugar concentration in the cotton sample.
With this method, suitable indications on the adhesion tendency of the cotton are obtained with the analogy process, but this test is very time consuming and requires expensive equipment, in particular if a large quantity of cotton samples are to be tested.
It is a further disadvantage that ratios have to be established each time between the photometric results and the experience gathered in operation with adhesion-prone cotton to ascertain to what degree a certain photometric result makes it possible to process the cotton, to process it under certain conditions, or whether unsustainable difficulties would result.
Another method to ascertain the adhesion tendency of cotton is the so-called "thermo-detection process". In order to obtain information on the behavior in process to be expected in the spinning plant, influenced by the adhesion tendency, the tendency of the cotton to adhere is simulated on metallic surfaces. Under the influence of heat and pressure upon the sample, the natural adhesion tendency is amplified and thus a longer exposure time is simulated. With this process, cotton flakes out of the bale and open cotton flakes and fiber slivers can be tested.
It is a disadvantage in this process that an expensive sample preparation is required. A uniform fleece in the format of the testing surface must be formed. The fleece is spread out on an aluminum film. Care must be taken so that the surface of the sample covers at least 95% of the testing surface. The sample spread out between aluminum films is finally placed on a pressing plate and is subjected to pressure and heat for 12 seconds. At the end of that period of time the heating plate must be lifted off immediately. This is followed by another two-minute pressing with the post-pressing device. The sample is then taken out of the device and, after a cooling period of at least 30 minutes, the upper film is carefully removed from the sample. The sample fibers which do not adhere on the aluminum film are carefully wiped off with a wiper by hand. The adhesion points remaining on the film, with adhering fiber bunches, are counted. Special conditions must also be adhered to for the counting in order to avoid counting mistakes. At least three individual tests must be made. If not at least two results fall into one adhesion tendency class and the third result into an adjoining class, the number of tests must be increased until two thirds of the test result can be assigned to one adhesion tendency class. Here, too, the disadvantage exists that this process is not only expensive, but that the relationship between the counting result and the experience of treatability must be established.